The girl left two suicide notes, one addressed to her classmates saying “now you’ll be happy” and the other asking her parents for forgiveness, Il Fatto Quotidiano reported.
The girl was found in the courtyard below by a neighbour.
She had been off sick from school for a week when her mother went into her room to give her an inhalation treatment, only to discover the room empty and the window wide open.
The girl, who was found conscious, told those paramedics and police first on the scene that she was having problems getting along with her classmates.
She is now in intensive care at Udine hospital with multiple fractures and possible spine injury.
Police are checking messages on her social media accounts to ascertain what might have triggered the suicide bid.